Grate the zucchini directly into a clean kitchen towel and squeeze out as much moisture as possible — wet zucchini makes soggy quesadillas that fall apart in the pan. Squeeze hard, then squeeze again. Set the dry zucchini aside.
Heat the olive oil in a large skillet over medium heat. Add the grated zucchini and cook for 3–4 minutes, stirring regularly, until any remaining moisture has evaporated and the zucchini is lightly golden. Add the drained corn, spring onion greens, ground cumin, paprika, and black pepper. Stir well and cook for another 2 minutes. Remove from heat and set aside.
Combine the sour cream, chopped coriander, chives, lemon juice, and black pepper in a small bowl. Stir well until combined. Taste — it should be fresh, herby, and slightly tangy. Set aside.
Wipe the skillet clean and return to medium heat — no oil needed. Lay one tortilla flat in the pan. Spoon a generous amount of filling onto one half of the tortilla and fold over. Press gently with a spatula. Cook for 2–3 minutes per side until golden and crisp. Repeat with remaining tortillas. Keep finished quesadillas warm in a low oven (100°C / 210°F) while you cook the rest.
Cut each quesadilla into 3 wedges. Divide between two plates and serve immediately with the herb cream alongside for dipping.